A Knowledge-Based System for the Dynamic Generation and Classification of Novel Contents in Multimedia Broadcasting
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24th European Conference on Artificial Intelligence - ECAI 2020 Santiago de Compostela, Spain A Knowledge-based System for the Dynamic Generation and Classification of Novel Contents in Multimedia Broadcasting Eleonora Chiodino1 and Davide Di Luccio2 and Antonio Lieto3 and Alberto Messina4 and Gian Luca Pozzato5 and Davide Rubinetti6 Abstract. In this work we exploit a recently introduced nonmono- requires, from an AI perspective, the harmonization of two conflict- tonic extension of Description Logics, able to deal with the prob- ing requirements that are hardly accommodated in symbolic systems lem of knowledge invention via commonsense concept combination, [7]: the need of a syntactic and semantic compositionality (typical of to dynamically generate novel editorial contents in the context of a logical systems) and the one concerning the exhibition of typicality real broadcasting company: RAI - Radiotelevisione Italiana, the Ital- effects. According to a well-known argument [20], in fact, prototypes ian public broadcaster. In particular, we introduce the system imple- (i.e. commonsense conceptual representations based on typical prop- menting such logic, i.e. DENOTER: Dynamic gEnerator of NOvel erties) are not compositional. The argument runs as follows: consider contents in mulTimEdia bRoadcasting (available online at the URL: a concept like pet fish. It results from the composition of the concept http://di.unito.it/denoter), that has been applied and pet and of the concept fish. However, the prototype of pet fish can- tested in the online multimedia platform of RAI (i.e. RaiPlay) as a not result from the composition of the prototypes of a pet and a fish: tool for both the generation/suggestion of novel genres of multime- e.g. a typical pet is furry and warm, a typical fish is grayish, but a dia on-demand contents and the reclassification of the available items typical pet fish is neither furry and warm nor grayish (typically, it within such new genres. Our system works by extracting the typical is red). The pet fish phenomenon is a paradigmatic example of the properties characterizing the available genres (with a standard infor- difficulty to address when building formalisms and systems trying to mation extraction pipeline) and by building novel classes of genres imitate this combinatorial human ability. In this paper, we exploit a as the result of a creative combination of such extracted represen- framework able to account for this type of human-like concept com- tations. We have tested DENOTER (i) by reclassifying the available bination and we show how it can be used as a tool for the generation contents in RaiPlay with respect to the new generated genres (ii) with and the suggestion of novel editorial content. In particular, we adopt an evaluation, in the form of a controlled user study experiment, of the recently introduced nonmonotonic extension of Description Log- the feasibility of using the obtained reclassifications as recommended ics (from now on DL, see [2]) able to reason on typicality and called contents (iii) with a qualitative evaluation done with a small group of TCL (typicality-based compositional logic) introduced in [15, 13]. experts of RAI. The obtained results are encouraging and pave the In this logic, “typical” properties can be directly specified by way to many possible further improvements and research directions. means of a “typicality” operator T enriching the underlying DL, and a TBox can contain inclusions of the form T(C) v D to represent that “typical Cs are also Ds”. As a difference with standard DLs, 1 INTRODUCTION in the logic TCL one can consistently express exceptions and reason about defeasible inheritance as well. Typicality inclusions are also Knowledge invention via conceptual recombination is an important equipped by a real number p 2 (0:5; 1] representing the probabil- generative phenomenon highlighting some crucial aspects of the ity/degree of belief in such a typical property: this allows us to define knowledge processing capabilities in human cognition. Such ability, a semantics inspired to the DISPONTE semantics [22] characterizing in fact, concerns high-level capacities associated to creative think- probabilistic extensions of DLs, which in turn is used in order to de- ing and problem solving. Still, it represents an open challenge in the scribe different scenarios where only some typicality properties are field of artificial intelligence [3]. Dealing with this problem, indeed, considered. Given a KB containing the description of two concepts CH and CM occurring in it, we then consider only some scenarios in 1 Dipartimento di Psicologia, Universita` di Torino, Italia, email: order to define a revised knowledge base, enriched by typical proper- [email protected] 2 Dipartimento di Informatica, Universita` di Torino, Italia, email: da- ties of the combined concept C v CH u CM by also implementing [email protected] some heuristics coming from the cognitive semantics. 3 Dipartimento di Informatica, Universita` di Torino and Istituto di Cal- In this work we exploit the logic TCL in order to dynamically gen- colo e Reti ad Alte Prestazioni, ICAR-CNR Palermo, Italia, email: anto- erate novel knowledge by means of a mechanism for commonsense [email protected] 7 4 RAI - Centro Ricerche, Innovazione Tecnologica e Sperimentazione, combination . This generative and creative capacity has been tested Torino, Italia, email: [email protected] 5 Dipartimento di Informatica, Universita` di Torino, Italia, email: gian- 7 Other works have already shown how such logic can be used to model com- [email protected] plex cognitive phenomena [15], creative problem solving [16, 12] and to 6 Dipartimento di Informatica, Universita` di Torino, Italia, email: da- build intelligent applications in the field of computational creativity [14]. [email protected] Alternative approaches to the problem of commonsense conceptual combi- 24th European Conference on Artificial Intelligence - ECAI 2020 Santiago de Compostela, Spain in the context of a real multimedia broadcaster (RAI - RadioTele- 2 THE DESCRIPTION LOGIC TCL FOR visione Italiana) as a tool for both the suggestion of novel genres CONCEPT COMBINATION of multimedia on-demand contents of the online platform RaiPlay (https://www.raiplay.it) and for the reclassification of the In this section we briefly recall the basic concepts underlying the CL available items within such new genres. We introduce the system logic T [13, 15], used in the system DENOTER as the basis for the DENOTER (Dynamic gEnerator of NOvel contents in mulTimEdia generation of new genres as the combination of two existing ones. bRoadcasting) which, first, automatically builds prototypes of exist- This logic combines three main ingredients. The first one relies on ing basic genres in RaiPlay (comedy, thriller, kids, horror, and so the DL of typicality ALC + TR introduced in [8], which allows to on) by extracting information about concepts or properties occurring describe the protoype of a concept. In this logic, “typical” properties with the highest frequencies in the textual descriptions of the multi- can be directly specified by means of a “typicality” operator T en- media contents available in the online platform8. Such prototypes are riching the underlying DL, and a TBox can contain inclusions of the formalized by means of a TCL knowledge base, whose TBox contains form T(C) v D to represent that “typical Cs are also Ds”. As a both rigid inclusions of the form difference with standard DLs, in the logic ALC + TR one can con- sistently express exceptions and reason about defeasible inheritance as well. For instance, a knowledge base can consistently express that BasicGenre v Concept; “normally, athletes are fit”, whereas “sumo wrestlers usually are not fit” by T(Athlete) v Fit and T(SumoWrestler) v :Fit, given in order to express essential desiderata but also constraints, for in- that SumoWrestler v Athlete. The semantics of the T operator stance Musical v Song (musical contents must have songs) and is characterized by the properties of rational logic [10], recognized Kids v :Blood (due to law restrictions, contents available for kids as the core properties of nonmonotonic reasoning. ALC + TR is must not contain blood), as well as prototypical properties of the characterized by a minimal model semantics corresponding to an ex- form tension to DLs of a notion of rational closure as defined in [10] for propositional logic: the idea is to adopt a preference relation among p :: T(BasicGenre) v TypicalConcept; ALC + TR models, where intuitively a model is preferred to an- other one if it contains less exceptional elements, as well as a notion representing typical concepts of a given genre, where p is a of minimal entailment restricted to models that are minimal with re- real number in the range (0:5; 1], expressing the frequency of spect to such preference relation. As a consequence, T inherits well- such a concept in items belonging to that genre: for instance, established properties like specificity and irrelevance: in the example, 0:72 :: T(Comedy) v Heaven is used to express that the the logic ALC + TR allows us to infer T(Athlete u Bald) v Fit typical comedy contains/refers to the concept Heaven with a fre- (being bald is irrelevant with respect to being fit) and, if one knows quency/probability/degree of belief of the 72%, and such a degree is that Hiroyuki is a typical sumo wrestler, to infer that he is not fit, automatically extracted by DENOTER from the description of mul- giving preference to the most specific information. timedia contents currently available on RaiPlay and marked as be- As a second ingredient, we consider a distributed semantics sim- longing to such a genre. ilar to the one of probabilistic DLs known as DISPONTE [23], al- Given the knowledge base with the prototypical descriptions of lowing to label inclusions T(C) v D with a real number between basic genres, DENOTER exploits the reasoning capabilities of the 0.5 and 1, representing its degree of belief/probability, assuming that logic TCL in order to generate new derived genres as the result of the each axiom is independent from each others.